Racial and Biological Diversity in Early Alzheimer Brain Markers

Investigators working within the Health and Aging Brain Study–Health Disparities (HABS-HD) imaging effort reported that early Alzheimer disease–related biomarker patterns differed across ethnoracial groups in a diverse cohort of older adults without dementia.

The research describes non-uniform tau PET signal in memory-related regions across Black, Hispanic, and non-Hispanic White participants, with higher medial temporal lobe tau reported in Black and Hispanic participants relative to non-Hispanic White participants, including among amyloid-negative individuals. In this account, the central observation is group-level variation in tau PET markers, with medial temporal lobe tau examined as an early Alzheimer disease–relevant biomarker rather than as a measure of progression over time.

The investigators analyzed brain imaging and memory testing from more than 1,500 older adults who were described as cognitively unimpaired or as having mild cognitive impairment. The authors reported higher medial temporal lobe tau PET signal in Black and Hispanic participants than in non-Hispanic White participants, with this difference most evident in cognitively unimpaired participants. They also noted that in amyloid-negative participants, Black and Hispanic participants showed higher medial temporal lobe tau than non-Hispanic White participants.

The report also states that higher tau signal was associated with worse memory performance overall across the cohort. It further describes a group-specific moderation pattern in which amyloid positivity strengthened the relationship between tau and memory in non-Hispanic White and Hispanic participants, but not in Black participants. These findings are presented as evidence that biomarker–cognition relationships varied across groups in this dataset.

The authors also highlighted scan-interpretation cautions. Tau PET tracer off-target binding was described as an important limitation, including choroid plexus signal that could inflate medial temporal measurements and meningeal signal that could contribute to apparent lateral temporal differences. In this framing, such scan-related signal sources were presented as one reason observed group differences in tau PET patterns might not always directly reflect underlying tau biology.

In discussing the reported group differences in biomarker–memory relationships, the authors suggested that contributors beyond amyloid and tau may shape memory differences in some groups. They cite vascular comorbidities, health conditions such as hypertension and diabetes, and socioeconomic or stress-related factors as examples of influences that may play a prominent role and warrant closer study.

The report also describes a call to carefully validate imaging tools in diverse populations and points to the need for future longitudinal work to better understand how tau, amyloid, vascular health, genetics, and social determinants interact over time. The next steps center on improving biomarker interpretability across populations through inclusive validation and longer-term follow-up.

Key Takeaways:

• Recent research reported higher medial temporal lobe tau PET signal in Black and Hispanic participants compared with non-Hispanic White participants in the HABS-HD cohort, with the difference most evident in cognitively unimpaired participants.
• Higher tau PET signal was reported to be associated with worse memory overall, with the summary describing differing amyloid moderation of the tau–memory relationship across groups.
• The authors cited choroid plexus and meningeal off-target PET signal as important caveats and emphasized inclusive validation of imaging tools plus future longitudinal work in diverse populations.